From: "Michael Heuer" <[EMAIL PROTECTED]>
> On Sat, 7 Jun 2003, Stephen Colebourne wrote:
>
> > Proposal #3 (Colebourne - merged from #1 and #2):
> > --------------------------
> > public boolean addAll(int index, Collection c){
> > if (preAddAll(index, c)) {
> > result = backingList.addAll(index, c);
> > postAddAll(index, c, result);
> > }
> > return result;
> > }
>
> I might be missing something here, but in order to support
> oldSize/newSize in the event object in this design, I think I'd have to
> pass some state from the pre to the post method, e.g.
I was thinking that the decorator could store the info as an instance
variable. It should work fine.
Stephen
>
> class AbstractXxxCollection
> extends AbstractCollectionDecorator
> {
> public boolean add(Object o)
> {
> boolean result = false;
> if (preAdd(o))
> {
> result = super.add(o);
> postAdd(o);
> }
> return result;
> }
> protected boolean preAdd(Object o) { return true; }
> protected void postAdd(Object o) {}
> }
>
> class ObservableCollection
> extends AbstractXxxCollection
> {
> protected boolean preAdd(Object o)
> {
> int oldSize = size();
> return true;
> }
> protected void postAdd(Object o)
> {
> fireElementAdded(oldSize, size(), o);
> }
> }
>
> something like,
>
> protected boolean preAdd(Object o, Map ctx)
> {
> ctx.put("oldSize", new Integer(size()));
> return true;
> }
> protected void postAdd(Object o, Map ctx)
> {
> int oldSize = ((Integer) ctx.get("oldSize")).intValue();
> fireElementAdded(oldSize, size(), o);
> }
>
> michael
>
>
>
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